Pillows on the market today are built in one of several different ways. Firstly, the pillow can be made from a randomly oriented filling material. An example of this construction is a pillow that is composed of randomly oriented polyester fiberfill. This construction is not limited to a randomly oriented polyester fiber, but can also include, but is not limited to, wool, cotton, or other fibers in which the material fibers are oriented in random orientations. It is also possible to construct a pillow from randomly oriented solid structures. This type of construction is consistent with pillows made from small foam blocks that are randomly dispersed inside the pillow casing. The foam elements can be made from, but not limited to, man-made foams such a poly foam or visco-elastic foam, to various types of natural foams such as latex foam. In addition to the random orientation of the foam elements, additionally the foam elements can consist of different sizes and shapes. It is also possible to mix different foam sizes and shapes inside of a single pillow covering to create an additional level of randomness.
A second type of pillow construction is made with one or more layers of sheet filling materials within a pillow casing. Examples of this type of pillow are layered poly foam pillows in which one or more types, as well as one or more layers of poly foam are stacked upon one another and then encased in a pillow cover. The layer(s) of foam material can be either man made, such as polyfoam or visco-elastic foam, or natural such a latex. In addition, the layers of sheet foam material can be cut into different contours to allow them to better fit into different body crevices or conforming contours. Also, part of this group of pillow construction is when one or more of the sheet foam layers are fabricated to have a non-uniform surface. A top layer of convoluted foam falls into this category. This type of non-uniform foam layers allows for increased airflow as against uniform surface sheet foam layer, and well as a more localized pressure reduction versus a standard sheet foam material.
A third type of pillow construction can be formed by the combination of types one and two (hybrid pillow). This type of pillow often encompasses, but is not limited to, a solid foam center surrounded by a randomly oriented fiberfill material. This type of construction has both the advantages and disadvantages of each respective pillow construction.
In all of the aforementioned pillow construction methods several benefits and corresponding shortcomings are evident. In the case of type one, the random fiberfill pillow construction, the random orientation of the filling material fibers allows for an airflow to be able to exist within the fiber construction and hence within the pillow. This allows the sleeper to not overheat when sleeping in a single position over a long period of time since air can flow within the pillow structure and around the sleeper's head. At the same time, the random orientation of the fiber filling allows the sleeper to “mold” the pillow to suit their particular needs. However, the randomness of the fibers, in allowing the pillow to easily mold, also makes the pillows resilience, or bounce back, both unpredictable and potentially compromised. This also results in a pillow that tends to “flatten out” over the course of a night's sleep. Many a sleeper will have to “fluff up” the pillow, by manually attempting to re-randomize the fibers, in an attempt to un-flatten the pillow and restore some of the pillow's original resilience. With regards to the type of construction made from small foam blocks that are randomly dispersed inside the pillow casing similar advantages and disadvantages already discussed also occur. The very nature of random orientation of the foam elements makes the pillow unpredictable in terms of resilience and in term of potentially flattening out.
The advantage of the second type of pillow construction, the uniform sheet layer filled pillow, is that this type of pillow has a uniform resilience and will not flatten out. The problem with the sheet foam pillow construction centers around two principle areas. Firstly, the very nature of sheet foam tends to restrict airflow. Even attempts to mitigate this issue by creating non-uniform, convoluted surfaces, still results in significantly reduced airflows versus non-uniform fiber filled pillows. This is due to the fact that even convoluted foam surfaces have a continuous foam layer beneath the convoluted layer that inhibits airflow. Additionally, the continuous sheet nature of this style of pillow does not allow spot pressure reduction. For instance, if a sleeper buries the side of their face in the pillow, areas of the face that protrude will be subjected to higher localized pressures due to the underlying sheet cushioning material not allowing for localized pressure reductions. Along these same lines, the ability of a solid layer cushioning material pillow to mold to a sleeper's anatomy is significantly reduced and compromised.